Refrigerant charge control system for heat pump

ABSTRACT

A geothermal heat transfer system having a plurality of heat exchange loops placed in the ground, each loop having an out flow line and a return line connected by a U-turn juncture. A heat exchange device connects to the loops through the inlet and outlet lines. A refrigerant charge control system selectively provides either heating or cooling heat transfer to or from a temperature regulated area. A charge control flow control device maintains a single flow direction of refrigerant within charge control system, while refrigerant flow reverses direction elsewhere in said heat pump system. A plurality of check valves are employed to provide the flow control. A float and stop valve system maintains a sufficient quantity of refrigerant in the condenser and evaporator of the heat pump for optimum design performance.

This is a continuation-in-part of application Ser. No. 08/580,469 filedon Dec. 28, 1995, now U.S. Pat. No. 5,634,515.

FIELD OF THE INVENTION

The invention relates to a heat-pump system, and more particularly, to asystem for providing the control of the refrigerant charge in aheat-pump system.

BACKGROUND OF THE INVENTION

The instant invention involves the use of the earth as a constant sourceof heat to be extracted by a heat pump. Geothermal or ground-source heatpumps, although costly to install, have been found to more efficientlyheat and air condition building spaces than other heat pumps. It is muchmore efficient to extract heat from a substance such as earth, which hasa near-constant temperature, than from air which can be subject tosevere temperature variations.

Prior art geothermal systems have utilized ground loops that have beeninstalled horizontally using open trenches. Horizontal installation,however, causes significant damage to the environment. Nature hassuffered from root-system damage and removal of vegetation caused by thehuge displacement of earth required by horizontal ground loopinstallation. Landscaping has often been destroyed by the largedisplacement of earth, removal of trees, shrubs, structures, and grass.Parking lots, driveways, sidewalks, and curbs have been removed,damaged, or their installation delayed for long periods of time to allowfor the settling that must occur after massive displacements of earth.Moreover, polluted run-off from the large excavations has disturbed theenvironment in areas beyond the job site. Furthermore, the hugeexcavating equipment is destructive in its weight, size, and pollutinguse of fossil fuels.

The installation of prior horizontal ground loops requires thesubcontracting of big, expensive equipment and specialized personnel toperform very time-consuming drilling, excavating of trenches, andinstallation. The equipment used for these excavations is extremelyexpensive and is not owned by many HVAC installers. The man-hoursrequired to install prior art horizontal loops is extensive and costly.Deep, dangerous ditches are dug and painstakingly prepared. Workers thenspend many hours installing specialized pipes and fittings. Finally, theditches are carefully filled and left for settling. Land that has had aprior art ground loop system installed must remain untouched for as muchas a year and a quarter to allow for settling. This is an unacceptabledelay to the installation of landscaping, parking lots, sidewalks,curbs, driveways, etc. The untouched ground is not only unsightly, butprovides dust which is carried by the wind to undesirable places (i.e.indoor surfaces, wet paint and caulk, lungs, eyes, etc.).

Many owners of modern homes and commercial buildings, as well as townhouses, condominiums, apartments, etc. have land areas that are toorestrictive for prior art horizontal ground loop installation. Manyhomeowners wishing to change to geothermal heating systems forego theconversion due to the destruction of existing landscaping and woodedareas as well as other improvements. The ditch excavation required forprior art ground loops is simply not feasible for homes located on rockyland.

The obvious next step is to install vertical ground loops. Verticalground loop installation requires the use of large cumbersome 6"vertical boring machinery mounted on large trucks weighing in at 15 tonsor more. Few people want these monstrous machines in their yards todestroy their driveways and landscaping. These machines are noisy, leavelarge piles of cuttings and muddy streams of run-off water. Thevibrations caused by the machinery can crack foundations and basementwalls when drilling near buildings. The depth of vertical bore-holes canpenetrate subterranean caverns and the water aquifer. State watercontrol boards have expressed a preference for horizontal instead ofvertical ground loops because of the greater threat to drinking watercontamination posed by the vertical loop installation. Furthermore, inthe case of cavern penetration, well inspectors will require cementtrucks to fill a large cavern. Cement is much too expensive to waste oncavern filling. The earth's crust is full of caverns and undergroundrivers, creating money pits for vertical ground-loop installers.

As with horizontal ground loops, the cost of vertical ground loops isprohibitive. Drilling or trenching equipment is not typically owned byHVAC professionals because it is unique and costs thousands to hundredsof thousands of dollars for one machine. The cost of casing, pipe,fittings, cement, bits, and drill stems required for vertical groundloops can be high. Substantial expense is further incurred in theman-hours required to install the vertical loop system in the bore-holesbefore they cave-in. During rainy seasons, a sea of mud can fillbore-holes the minute the drill bit is pulled, rendering the bore-holesuseless. The large, 6" bore-holes must also be filled with somesubstance to facilitate the conduction of heat between bore-hole wallsand the heat transfer medium-carrying pipe. This substance is a costlyone not needed in the instant invention.

Although vertical ground loops have been put in places where prior arthorizontal loops have not been feasible, the small yards of many homeshave still been off limits to huge drilling equipment. Thus, because ofdestruction to landscaping and size and weight of water wellconstruction drill rigs, in some rocky soil, vertical ground loops havenot been feasible or desired in many cases.

Additionally, vertical ground loops have suffered from design problems,i.e. poor flow distribution, velocity problems and liquid or oilaccumulating in the bottom of the vertical ground loops. Moreover, asimple, inexpensive way of preventing flash gas from occurring whensupply and return conduits are in the same bore-hole has heretofore beenunobtainable.

Also of paramount importance is the superiority of direct-exchange (DX)geothermal heat pump systems over indirect-exchange systems. Inindirect-exchange systems (water-source), additional pumps to circulatea liquid other than the refrigerant in an additional indoor heatexchanger results in greater pump horse power being required. Anadditional heat exchanger is required because the transfer of heat goesfrom ground to ground-loop liquid (water) to refrigerant to air. In DXsystems, however, the heat goes from ground to refrigerant to air, thuseliminating not only a heat exchanger and various pumps, but also thebothersome water and anti-freeze mixture in the ground-loop.Furthermore, the plastic pipe used in prior art water-sourceground-loops has been large, cumbersome, crinkled easily, and providedtoo much resistance when being inserted into bore-holes.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the instant disclosure will become more apparent whenread with the specification and the drawings, wherein:

FIG. 1 is a schematic illustration of a site plan for the installationof the geothermal heating and air conditioning system of the instantinvention;

FIG. 2 is a top view of the laminar flow divider used with the instantinvention;

FIG. 3 is a side view of the laminar flow divider of FIG. 2;

FIG. 4 is a top view of the liquid-oil-gas separator of the instantinvention;

FIG. 5 is a side view of the liquid-oil-gas separator of FIG. 4;

FIG. 5A is a top view of the cup and piping of the liquid-oil-gasseparator of FIG. 5;

FIG. 6 shows a top view of the U-bend assembly of the instant invention;

FIG. 7 shows a side view of the U-bend assembly of FIG. 6;

FIG. 8 shows a top view of the 180° U-Bend Elbow;

FIG. 9 is an end view of the pipe entrance end of the U-bend elbow ofFIG. 8;

FIG. 10 is an end view of the closed end of the U-bend elbow;

FIG. 11 is a side view of the U-bend elbow;

FIG. 12 is a side view of the drill bit and stem of the instantinvention;

FIG. 13 is an end view of the bit-end of the drill bit and stem;

FIG. 14 is a cross-sectional side view of the earth drill water swivelassembly;

FIG. 15 an end view of the earth drill water swivel assembly;

FIG. 16a is a schematic illustration of the heat exchange system in theair conditioning cycle;

FIG. 16b is a schematic illustration of the heat exchange system in theheating cycle;

FIG. 17 shows the optional U-bend assembly of a concentric water-sourceground-loop,

FIG. 18 shows optional duct work for a radiant floor addition to theinstant heat pump;

FIG. 19 is a right side view of the charge control system of the presentinvention;

FIG. 20 is a right side view of the charge control system with a cutaway section showing the float assembly's internal parts; and

FIG. 21 is a front view of the charge control system showing the flow inheating mode of the heat transfer of gas (i.e. freon).

DETAILED DESCRIPTION OF THE INVENTION

The instant device overcomes the prior art deficiencies by providing adirect-exchange ground-source heat pump that is easy and inexpensive toinstall without destruction to the environment.

The installation method for the disclosed ground-source heat pump causesvirtually no damage to the environment or existing structures. No largeexcavations are required as the horizontally oriented bore-holes areextremely small. The small bore-holes do not bother subterraneancaverns, water aquifers, grass, trees, shrubs or any landscapevegetation. Structures and paved surfaces also remain free from damage.Due to the bore-hole size, a waiting period between installation andconstruction to allow the earth to settle is not required. The equipmentused in the installation is handheld and affordable. As the equipment ispowered by electricity, there are no fossil fuels to be spilled orburned to pollute the environment. Further, as installation does notrequire the moving of mass amount of land, polluted run-off from thelarge excavation of the prior art are eliminated. The disclosureachieves EPA and DOE projected goals for geothermal technology to cleanup the environment and significantly reduce the over-use of fossilfuels.

In geothermal heat-pump systems, the exchange of heat takes placebetween the earth and medium-carrying conduits that are placedhorizontally or vertically in the ground. Heat exchange can be eitherdirect or indirect, however, direct exchanged geothermal heat pumpsystems provide a superiority over the indirect systems. The use ofdirect heat exchange eliminates the need for extra pump horse power topump an extra liquid, as required in indirect systems such aswater-source ground loops. An additional heat exchanger is alsoeliminated since the transfer of heat goes from ground to refrigerant toair. This eliminates not only an heat exchanger and various pumps, butalso the dangerous water and anti-freeze mixture required in indirectexchange ground loops. Additionally, the transfer of heat to the air ina building utilizing a heat pump can be simultaneously transferred bythe same heat pump system to the domestic hot water used in thebuilding. The instant invention provides the additional benefits ofon-demand domestic hot water production, and air dehumidification.Further, the instant invention can readily be used with radiant floors.Because typical basements have cold, damp, concrete floors, the use ofradiant floors provides a comfort level unparalleled in basements. Aradiant floor system takes the chill from the floor as well as removingdampness.

In FIG. 1 a heat pump 10, illustrated in detail in FIG. 16, is connectedto a supply air duct 32 and a return air duct 30. The heat pump 10 is inheat transfer connection with a domestic hot water heater 40 by way of ade-super heater 38, using standard water pipes 252 and 254. Thecompressor 50 compresses the vaporized heat transfer medium (R-22 orother refrigerant known in the art) producing a very hot gas, and causesthe hot gas to flow out through transfer line 160 into the flow divider70. Although the heat transfer medium is referred to herein as R-22,water or freon, it should be noted that any medium applicable to thesystem as taught herein can be used. Depending upon the size of thesystem, one or more pair of flow dividers 70 are installed in the headerditch 60 to disperse the medium to the ground loops 80. One of each pairof flow dividers 70 is used to divide the flow from the building throughtransfer line 160 equally among the plurality of ground loops 80. Thereturn flow is combined in the second flow divider 70 of the pair andreturned to the house via conduit 166. Since the flow direction reversesbetween the heating and cooling cycles, the flow dividers 70 are used inpairs so that the flow to the ground loops 80 is always uniformlydistributed from the single line to the plurality lines by means of theflow dividers 70. The flow dividers 70 discharge upwardly for laminarflow of gas and liquid to "U"-bend assemblies 80, in order to provideequal, uniform distribution to each assembly 80. The U-bend assemblies80 are placed in bore-holes 90 drilled by carbide-tipped bits/stems 100.The number of bore-holes 90 is determined by the size of the structureand heating system. The bore-holes 90 used in conjunction with the 1/2inch conduit would be about 7/8 inch. The bits 100 are manufactured tobe used in conjunction with a hand-held air- or electric-powered powerdrill 110, earth drill water swivel 120, and booster pump 130. The drill110 can be a standard 500 to 1000 rpm, 110-volt, 1/2 horse power drill.The booster pump 130 should have the capacity to deliver approximately15 psi at 3 gal. per min. and is connected to the water supply throughuse of a standard hose 134.

Bore holes 90 are two or three feet deep at the header ditch 60descending to approximately eight to eighteen feet deep. The bore holes90 generally extend for twenty to eighty-feet, depending on geologyencountered. The angle of the bore hole with respect to a horizon isgenerally in the range from about 5 to about 15 degrees. Althoughsteeper angles can be used, the shallow angle of 5 to 15 degrees ispreferred. To start the bore-holes 90, the drill operator simply walkshorizontally along the terrain. The drill bits flex the small angle ofdecent, However, the first ten feet of bore-hole must be straight. Whilespinning at 800 rpm or so, the bit will remain straight.

The pump 130 pumps water through steel drill stems 100, illustrated infurther detail in FIGS. 12 and 13. The drill stems 100 are welded orthreaded together in multiple lengths of 20', 40', 60', and 80'. Thedrill stems 100 are threaded to the earth drill water swivel 120 inorder to drill the bore holes 90. Preferably three 200 foot passes ofU-bend assembly containing R-22 are provided per ton of building airconditioning load requirement. The length of passes will vary accordingto geology encountered in that rock yields excellent heat transfer, claygood transfer and sand average heat transfer. An examination of thecuttings coming out of the bore-holes during the drilling process willhelp determine the need to increase or decrease the number of U-bendassembly passes. House water 134 will assist the drilling procedure bycarrying drill cuttings from the bore hole annulus to the header ditch60. The header ditch 60 should be excavated to a depth of 5' or more toaccommodate excess water and drill cuttings, where they settle andremain. U-bend assemblies 80 can be made on the job site to accommodatethe size and length of the multiple bore-holes. The number of bore holesis further determined by the number of equal length passes thathydraulically balance every laminar flow divider pass from dischargeline supply and liquid line return. Properly sized and insulated liquidlines 166 and discharge lines 160 that feed the supply and returnlaminar flow dividers are then drilled into the house from the headerditch 60. The feeder lines 166 and 160 continue the flow of eitherearth-cooled, or earth-heated, R-22 to and from the heat pump 10.

While in the air conditioning cycle (AC), as illustrated in FIG. 16A,the refrigerant in the ground loop 80 flows to the incoming laminar flowdivider 70 located in the header ditch 60. The refrigerant then travelsto a flow control piston 248, to the correct charge control system 242,and to another flow control piston 250. From the second flow controlpiston 250, the refrigerant goes to the coil 244 where the fan 243 movesbuilding air across the R-22 chilled evaporator coil 244. Therefrigerant moves to the reversing valve 246, on to the liquid-oil-gasseparator 170 to the compressor 50 and the de-super heater 38. The heatfrom the de-super heater 38 can be diverted for use in a domestic hotwater heater 40 by means of piping 252 and 254. A pump 256 draws theheated water from the de-super heater 38 to the hot water heater 40. Thewater is returned to the de-super heater 38 through return pipe 252. Therefrigerant repeats the trip through the reversing valve 246 to bereturned to laminar flow divider 70 and on to the ground loop 80 onceagain. In the heating cycle the flow is reversed by the building'sthermostat season selector switch that controls the reversing valve 246.

Reversing the direction of the reversing valve 246 creates the heatingcycle, as shown in FIG. 16B. The flow control piston 248 moves to theorifice restriction position, and flow control piston 250 to full flownon-restricting position. The correct charge control system 242 isinfluenced to feel back pressure and causes the R-22 refrigerant toexpand flash gas. This flash gas creates a large threshold of heatexchange medium in the evaporator. Where the correct charge controlsystem (CCCS) is electronically censored, the flow pistons are used inconjunction with the correct charge control system, however, if ahydraulic expansion device is build into the CCCS or other means knownin the art are utilized, the flow pistons are not required.

In the heating cycle, FIG. 16B, the heat transfer medium is heated inthe ground loops 80, and then in the compressor 50. Heat is removed inthe de-super heater 38 and then in the building air heat exchanger 244,before returning to the ground loops 80, for reheating.

FIGS. 2 and 3 show the laminar flow dividers 70 that serve to equallydivide the refrigerant received from the feeder lines 166 and 160 intothe proper number of conduits 84 found in the ground loops 80. For easeof description, the flow divider 70 connected to the feeder line 160will be referred to as the outgoing divider 70 and while the divider 70receiving the feeder line 166 will be referred to as the incomingdivider 70. As stated heretofore, the laminar flow dividers areinstalled in pairs, one to connect the conduit 84 of the ground loops 80to the feeder line 160 and the other to connect the conduit 86 of theground loops 80 to the feeder line 166. The laminar flow divider 70 hasa body 72 which receives either the feeder lines 160 and 166. The body72 of the laminar flow divider 70 is dimensioned to receive the conduits84 and 86. The refrigerant travels out conduit 84 and return throughconduit 86 of the ground loop 80. The return conduit 86 is connected toincoming divider 70 which converges the conduits 86 into one returnfeeder line 166. It should be noted that depending upon whether thesystem is in the heat or air conditioning mode will determine which ofthe feeder lines 160 or 166, as well as flow dividers 70, is theoutgoing and which is the incoming.

FIGS. 4, 5 and 5A show the liquid-oil-gas separator 170 which separatesthe refrigerant into its various states, allows oil to return to thecompressor and keeps liquid refrigerant from damaging the compressor.The separator 170 provides dual sight glasses 172 and 174 to allow forvisual liquid level charge adjustment verification. The dual sightglasses 172 and 174 provide the advantage that the HVAC specialist canpeer through sight glass 172 while shining a flash light into the othersight glass 174.

The liquid-oil-gas separator (LOGS) will separate oil from the freon,returning the oil to the compressor. A major problem with refrigerantcompressors is the migration of oil from the compressor and theresultant failure of the compressor. The separator 170, as illustratedin FIG. 5, is a cylindrical unit having an outer cylinder 62, a cylindertop 52 and cylinder base 53. The inflow pipe 51 is secured to thereducing T 63 and receives the liquid-oil-gas mixture. The inflow pipe51 extends into the cylinder 62 approximately one quarter the length ofthe cylinder 62. Two holes are drilled into the bottom of the cup 49 anddimensioned to receive the two L-shaped tubes 48. Since the tubes 48 aresubsequently secured to the inflow pipe 51, the distance between thetubes 48 is equal to the diameter of the inflow pipe 51. It ispreferable that the interior dimensions of the cup 49 be equal to thediameter of the inflow pipe 51 plus the diameter of the two tubes 48.The tubes 48 are preferably secured to cup 49 approximately 1 inch belowthe upper edge of the lip. The tubes 48 and cup 49 are oriented so as tobe suspended approximately 1/2 inch above the interior LOGS base 53. Thehorizontal legs of the tubes 48 have multiple holes 59 drilled alongtheir length. A deflector plate 50 is secured to the inflow pipe 51 todirect the mixture received from the input pipe 51 to the bottom of thecylinder 62. The cup 49, as illustrated, is approximately four incheslong, extending to within about one inch from the deflector plate 50.The deflector 50 is spaced about 5/16" from the upper edge or lip of thecup 49. The tube separator 54 is attached to the tubes 48 approximately21/2 inches from the cylinder base 53. The tube separator 54 serves toestablish the lower limit of the liquid freon 55 and therefore should bepositioned so that a sight glass view the separator 54 and the liquidfreon level 55 reveals an average charge, or acceptable level. Themaximum level of the freon 55 can be seen through sight glasses 172 and174 when using a flash light and must not exceed a running level whichis above the top of the cup 49.

Freon flows into the LOGS separator 170 through the tube 51 and isdeflected by the base of the cup toward the deflector 50. A "VENTURI"suction is produced by the fluid flow past the outlet of the tubes 48.The suction draws oil which accumulates at the bottom of the cylinder62, through the holes 59 in the legs of the L-shaped tubes 48 into thestream of flow of freon from the tube 51. The oil and freon gas is drawninto the compressor return line 56 and returned to the compressor, whilethe liquid freon 55 rains down off of the deflector plate 50. It appearsthat the oil is atomized so that it can become entrained in thecombination liquid, gas and oil flow stream to outlet pipe 56.

The rain like stream of liquid does not obstruct the ability to view thetop of the accumulated liquid 55 thereby enabling a user to determinethe level of the freon. The R-22 liquid being lighter than oil rains tobottom of the LOGS cylinder 62 to be accumulated there in reserve. TheLOGS cylinder 62 is preferably thermally insulated 57, through anyapplicable method known in the art. Reducing tee 53 is welded tocylinder top 52 slightly off center so as to allow 3" spacing of twosight glasses 172 and 174. The level of liquid will vary between the airconditioning cycle and the heating cycle and is monitored through thewindows 172 and 174.

FIGS. 6 and 7 show the U-bend assembly 80 that is placed into the groundand used to transport the refrigerant. The ends of the conduits 84 and86 then are placed into the 180° U-bend elbow 125. A strip of insulationmaterial 82, such as cut from a rubber under-ground soaker hose, isplaced between the two pieces of conduit 84 and 86. The insulationmaterial 82 and conduits 84 and 86 are maintained in position bysecuring the combination, by, for example, being wrapped in moistureresistant tape 88.

FIGS. 8, 9, 10 and 11 illustrate in more detail the 180° U-bend elbow125. The elbow 125 is made from a section of conduit having a diametersufficient to accommodate the conduits 84 and 86. One end 126 of theelbow 125 is crimped closed. The preferred length of the elbow 125 whenused in combination with 1/4 inch tubing, is approximatelyone-and-a-half-inches long with a 1/2 inch diameter. The crimped end 126must be sealed to prevent the escape of refrigerant which can beachieved through use of solder, or other means known in the art. As canbe seen in FIG. 11, the crimped end 126 forms a modified V-shape whichallows for easier insertion into the bore holes 90. It has been foundthat the taper of the V-shaped end 126 permits the length of conduit tobe passed through a relatively small diameter hole without binding. Itis noted that the greater the diameter of the bore hole the easier it isto pass long lengths of conduits without binding. However, the abilityto bore long holes is inversely related to the diameter of the holebeing bored. Thus, the use of the taper provides an advantageous balancebetween bore hole diameter and pipe diameter, thus maximizing the easeof boring a hole (by enabling a small diameter hole to be used) andmaximizing the length of conduit which can be inserted into therelatively small diameter hole. The conduits 84 and 86 are inserted intothe open end of the elbow 125, crimped and sealed. The conduits 84 and86 are prevented from sliding to the crimped end 126 by the deformationcreated during the crimping of the end 126. This "space" 128 allows forthe refrigerant to travel from conduit 84 to conduit 86 for the returntrip. The diameters of conduits 84 and 86 as well as the elbow 125 aregauged to reflect the required flow rates and heat exchange resultsbetween the earth and heat pump.

FIGS. 12 and 13 show the drill bit and stem 100. The stem 102 has athreaded end 104 which is dimensioned to interact with the water swivel120. The stem 102 is manufactured from a standard water pipe, preferablyschedule 80, with a diameter greater than that of the U-bend assembly80. The bit receiving end 112 is closed and rounded. A groove can be cutinto the stem 102 to receive carbide bit 106. The carbide bit 106 issoldered, or otherwise secured, to the bit receiving area 112. Two waterports 108 are drilled into the stem 102 to allow the water coming downthe stem 102 to exit into the bore-hole 90. Using the dimensionsdisclosed herein, the water ports are approximately 3/16 inch indiameter. Water serves to cool the bit and stem 100, carry cuttings tothe header ditch 60 and generally facilitate the drilling process. Whenusing the foregoing with water-source concentric conduits rather thandirect exchange, the diameters and length may require increasing.

FIGS. 14 and 15 show the earth drill water swivel 120. Water from thebooster pump 130 enters the swivel 120 at fitting 133. For ease ofmanufacture, the fitting 133 is preferably a standard fitting which willconnect to a 1/2 inch garden hose, although special fittings can be usedto allow for specialized applications. Water then travels through a ring124, which is held in place over the core 126 by a snap ring 128, orother means known in the art. It is preferable that the ring 124 be abrass donut commonly used in the art, however alternative rings can beused which provide the same advantages. Two "O"-rings 132 keep waterfrom escaping between the donut 124 and the spinning core 126. Waterenters the hollow center of the core 126 by way of a water port 136 andexits the core through the stem port 138. The stem port 138 is threadedto receive the threaded end 104 of the drill bit and stem 100. The drillconnector 140 is threaded to attach to the electric drill 110 with theaid of wrench flats 142. The rotation of the electric drill 110 causesthe core 126 to rotate within the ring 124, thereby rotating the drillbit and stem 100.

FIG. 17 illustrates a counter-current heat exchange system for use as aground loops heat exchanger. Fluid flow can enter conduit 505 which isrelatively rigid copper tube having a plurality of outlet ports 506. Theflow then returns, counter-current to the inlet flow. The flow in theregion between the outer tube 504 and the inner conduit 505 is in heatexchange with the ground for heating of the fluid in the winter and thecooling of the fluid in the summer. The outer tube is preferably, a layflat irrigation tube. Preferably, the tube is of polyethylene, but canbe of other flexible, high durability material. The inner copper tubeprovides the rigidity for the insertion of long length of conduit. Theend of the conduit 505 can be closed off by means of a conventional endcap 507 which is soldered in place, or a threaded end cap. Thepolyethylene tube 504 is clamped to the capped end of the copper conduitby any of the known clamping mechanisms, such as hose clamps. Clampingof the conduit 504 to the copper T 502 can be by the same means as theclamping at the capped end.

A copper "T" 502 provides the closure at the end opposite the cappedend. The copper T 502 is soldered to the copper tube 505 to provide afluid tight seal, at 512. Similarly, the copper T is solder connected toanother copper pipe 501, as well known in the art. The counter-currentheat exchange conduits can be advantageously used with heat exchangefluids, such as water-anti-freeze mixtures. Since the outer tube 504 iscollapsed during the installation process, there can be substantialclearance between the tube 504 and the wall of the bore hole into whichit is being inserted. Filling the conduits with fluid inflates theconduit 504 and brings its outer surface into heat exchange contact withthe earth. The force of the inflation of the conduit can compact thesurrounding earth. Therefore the expanded diameter of the conduit 504can exceed the diameter of the receiving hole, as bored, depending onthe type or condition of the earth.

The heating system can be advantageously used in conjunction withradiant floor heat exchange coils in concrete floor. Air from the forcedair duct system 430 and 432 shown in FIG. 18 will provide for the flowof sufficient air to remove the chill from a 6" insulated concrete floorslab using 2"×3" aluminum rectangular 0.029 conduit 460. Conduit 461 isa supply line and 462 is return flexible 6" duct. Shut off dampers 463control the air flow with the aid of the room's wall thermostat. Theconcrete floor can have approximately 1" of load bearing styrofoaminsulation underneath. Alternatively, 3/4 inch polybutalene water pipescan be embedded in the concrete. A circulator pump from the domestic hotwater heater and a wall thermostat can be used to control the flowrelative to the temperature of the room. The same radiant floor conceptcan be used in rooms such as kitchens and bathrooms where bare feetoften touch the floor. The pipes are simply attached to the sub-floormaterials and then insulated underneath.

Floats and bypass valves have been applied to refrigeration equipmentfor many years, but never uniquely applied to a unique DX system likethat of the above described heat pump.

As described above, the heating mode is changed to cooling mode by meansof a reversing valve in the heat pump system. When this reversing takesplace, the refrigerant flows in the opposite direction everywhere in theheat pump except in the charge control system, as illustrated in detailin FIGS. 19, 20, and 21. The maintenance of this constant flow directionin the charge control system is made possibly by the four check valves604a, 604b, 604c and 605d. Furthermore, it correctly charges the systemwith the optimum refrigerant status across condenser and evaporator.This correct charge across condenser and evaporator is paramount tooptimum performance in any refrigeration system regardless ofapplication.

As illustrated in FIG. 21, in the heating mode the flow of heat transfergas (e.g. freon) coming from the indoor condenser of the heat pump,described heretofore, enters through tube 601 into the tee 602, throughthe connector tube 603, and into the valve 604a. The valve 604a can beany appropriate one-way valve, such as a Watsco valve # MS-60R-8 or anapproved equivalent type by Henry. The flow from the valve 604a proceedsthrough the elbow 605 to the tee 606, through the tube 607 to the tee608 (FIG. 20), to tube 609, and into the float assembly 610.

The float assembly 610 contains a float 611 attached to a stop valve611a, which rotates on a hinge pin 613. The hinge pin 613 is the onlypoint of movement and friction in the charge control system. Therefrigerant liquid 600, as shown in FIG. 20, lifts the float 611,thereby allowing liquid to pass freely through opening 612 into the pipe614b. The inlet port, or opening, 612 provides for full flow when openand when closed, through contact of the stop valve 611a, provides forrestricted refrigerant gas flow through the inlet port 612. The inletport 612 has a diameter in the range of about 1/32 of an inch, but canrange in size, from about 0.03 inch to about 0.10 inch. The restrictedflow is provided to keep the condenser and evaporator of the abovedescribed heat pump flooded with refrigerant gas for optimum designperformance. The charge control system of the instant inventionautomatically maintains the correct refrigerant charge in the system.The maintenance of the correct charge is critical to the designperformance of a direct exchange or direct expansion (hereinafterabbreviated as DX) geothermal heat pump, especially those using theliquid-oil-gas-separator (LOGS) of previously described heat pump. Therefrigerant gas 600 released by the stop valve 611a into the inlet port612, continues through the tubes 614a and 614b, the tee 615, theconnector tube 616, the tee 617, the elbow 618 and through the checkvalve 604c. The check valves 604a and 604b maintain the refrigerant toalways flow through the float assembly 610 in the same direction,whether in the heating or cooling mode. Refrigerant continues throughthe tube 619, the tee 620, the port tube 621, and to the outdoorevaporator of a DX heat pump such as disclosed above, or otherrefrigeration devices, in addition to DX geothermal heat pumps.

In the cooling mode the refrigerant enters through port tube 621 andfollows the illustrated flow, entering the float assembly 610 throughvalve 604b and exiting the system through valve 604d.

The refrigerant is prevented from "back tracking" by the pressurecreated within the system. Since the valves 604 are one way, therefrigerant cannot enter the valves in the direction opposite the arrowsA. The pressure build-up therefore forces the refrigerant in the correctdirection at each of the tee joints.

The valve 622, (e.g. Sporlan # ADRIE-1, ADRSE-2, or competitors'equivalent) allows the bypass of refrigerant around the float assembly610 under conditions where suction pressure needs to be maintained andcontrolled. Such control of pressure is part of the charge controlsystem of the present invention's ability to quickly raise to an optimumrunning level, the performance of the refrigeration device to which itis attached. The valve 622 modulates the pressure from about 15 psi toabout 78 psi when needed to get the system up and running quickly.

The sight glass 623, shown in FIG. 19, enables service technicians toknow whether refrigerant is in a liquid or gas state. The sight glass623 also provides visual verification as to whether the float 611 isfunctioning properly, that is, whether the float is modulating thecharge control system for optimum balance of a gas-filled condenser anda liquid-flooded evaporator.

The instant invention will also work with existing art water sourceground loops by drilling bore-holes of approximately two inches indiameter and inserting a copper supply water tube into a return conduitmade of flexible irrigation plastic polyethylene as shown in FIG. 18.After inserted into the bore-hole the outer conduit is inflated insidethe bore-hole by 12 psi water pressure. A "U"-bend at the end of theconcentric conduits acts as a 180° elbow. It should be noted that awater-source ground-lop requires about twice as much underground pipingas does direct exchange ground loop.

As can be seen from the foregoing, through the use of this invention,the installation of ground loops no longer requires the use of big,heavy, expensive equipment and specialized personnel to perform verytime-consuming drilling, excavating of trenches, and installation. Thesmall, inexpensive equipment required in this invention can easily be ormay already be owned by many HVAC installers and contractors. Moreover,the man-hours heretofore required have been greatly reduced. Drillingequipment is effective, common, clean, small, inexpensive, and uses verylittle energy. Deep, dangerous ditches for the laying of pipes are notneeded. Pipes and fittings are simple and quickly prepared. The landthat has had the ground loop of this invention installed is immediatelyavailable for landscaping work, parking installation, or what ever istypically needed in residential or commercial areas. This high speedfactor of the installation process renders the system extremely costeffective for modern contractors and HVAC specialists. Furthermore,virtually no dust is created for wind to carry to undesirable places(i.e. indoor surfaces, wet paint and caulk, lungs, eyes, etc.). Theestablished neighboring inhabitants and their possessions remainunaffected.

Few home or building owners have land that is too restrictive for theinstallation of the geothermal ground loop system of this invention.Even the smaller lots of modern buildings such as town houses,condominiums, apartments, commercial buildings, etc. provide thenecessary land area for this invention. Owners of existing buildingswishing to change to geothermal heating systems can now have geothermalheating and cooling and domestic hot water without disturbing theirexisting structures, landscaping, wooded areas or neighbors. Moreover,building owners having rocky land can greatly benefit from thisinvention because as the small size of the bore-holes and thecharacteristics of the special drilling equipment allows for drilling inrock.

By virtue of the bore-holes having a near-horizontal orientation, wateraquifers and underground caverns will not be penetrated. Therefore thereis no fear of drinking water contamination and underground caverns willnot have to be filled with expensive cement.

The small copper conduit preferably used in this invention is the idealchoice for ground loops. The copper conduit is common, affordable,easily handled, and enduring, as illustrated by 5000 year old copperfound buried in Egypt. Additionally, copper tubing slips easily intobore-holes when fitted with the special 180° "U"-bend elbow fitting. Theclose tolerance bore-hole used herein has sufficient wet mud tolubricate and grout the U-bend assembly. When connections are made usingsolder, it is critical that the solder be able to resist corrosion. Asolder containing 60% silver provides the required strength whilepreventing corrosion.

This invention overcomes the costly, defective design problems of thedirect-exchange (DX) systems of the prior art. While verticalground-loops have suffered from poor laminar flow distribution andvelocity problems, the ground loops of this invention are not verticalin orientation and do not have these problems.

The foregoing identified superior aspects of this invention makes it themost environmentally responsible and cost saving heat pump commerciallyavailable and brings geothermal heat and cooling well within the reachof the average homeowner, and well within the skill and financiallimitations of the average contractor and HVAC specialist. The DX heatpump disclosed above is affordable for homeowners and profitable forcontractors and HVAC installers. The ability to eliminate the use of a$250,000 drilling rig and $150,000 excavating equipment enablesenvironmentally friendly geothermal heating systems to be made availableto a much wider range of consumers. General contractors will be willingto install geothermal heat pumps since the instant system will no longerdisrupt and delay the building process. Even when altered to apply towater-source ground-loop installations, which takes twice the amount ofbore-hole and land than the preferred embodiment, the instant method isstill micro surgery compared to prior art methods.

The foregoing dimensions are used in way of example only. In instancesobvious to those skilled in the art, the dimensions may requirealterations. Other materials which will meet the criteria set forthherein can be substituted.

What is claimed is:
 1. A refrigerant charge control system for use in aheat pump system, which selectively provides either heating or coolingto a temperature regulated area, the improvement comprising;reversingvalve means for changing between a heating mode and cooling mode of saidheat pump system, transfer gas charge control means, said charge controlmeans having an inlet for receiving transfer gas, a reservoir, and anoutlet, said outlet having flow control means for regulating the flow ofsaid transfer gas to maintain a predetermine level of transfer gas inthe system, and charge control flow control means for maintaining asingle flow direction of transfer gas into said refrigerant chargecontrol means, when transfer gas flow reverses direction into and out ofsaid charge control flow control means.
 2. The charge control system ofclaim 1, wherein said charge control flow control means further includesa plurality of check valves, said plurality of check valves preventingthe reversal of flow of said transfer gas to said refrigerant chargecontrol means while allowing reversal of flow to and from said chargecontrol flow means.
 3. The charge control system of claim 1, whereinsaid flow control means is a float valve, said float valve including afloat means, said float means being movable between a first openposition and a second closed position, and providing for full flow whenin the open position and when closed providing for restrictedrefrigerant gas flow.
 4. The charge control system of claim 3, whereinsaid restricted refrigerant gas flow is through an opening in the rangefrom about 0.03 inch to about 0.10 inch.
 5. The charge control system ofclaim 4, wherein opening is about 1/32 of an inch.
 6. The charge controlsystem of claim 3, wherein said heat pump system includes a heat pumpand an evaporator, and wherein said restricted flow is of a sufficientrate to keep the condenser and said evaporator of said heat pump floodedwith refrigerant for optimum design performance.
 7. The charge controlsystem of claim 2, wherein said system comprises a first flowinlet-outlet port, a first pair of check valves, a first flow splitterreceiving flow from said first flow inlet-outlet, said first flowsplitter being positioned between said first pair of check valves andreceiving flow from said first pair of check valves in a singledirection, whether functioning as an inlet or outlet, a second flowsplitter, said second flow splitter being positioned in the outlet flowline from one check valve of said first pair of check valves, a thirdflow splitter, said third flow splitter being positioned in the inletflow line from a second check valve of said first pair of check valves,a float valve, said float valve including an inlet port and float means,said float means being movable between a first open position and asecond closed position, and providing for full flow when in the openposition and when closed providing for restricted transfer gas flow,said float valve being position in a flow line between said second andsaid third flow splitters, a second pair of check valves and a fourthflow splitter, said fourth flow splitter being positioned between saidsecond pair of flow valves, said second pair of check valve actingtogether to provide flow in a single direction, one of said second pairof check valves receiving flow from said third splitter and a second ofsaid second pair of check valves providing flow to said second splitter.8. The charge control system of claim 7, further comprising a valvedbypass flow line between said second splitter and said third splitter,said bypass flow line providing for the bypass of transfer gas aroundsaid float valve under predetermined conditions thereby providingsuction pressure maintenance and control.